Web tension controlling means for use in association with printing machines



Aug. 12, 1958 A. M. HALLEY 2,847,210

WEB TENSION CONTROLLING MEANS FOR USE IN ASSOCIATION WITH PRINTING MACHINES Filed Dec. 6, 1954 5 Sheets-Sheet 1 ATTORNEYS Aug. 12, 1958 A. M. HALLEY 2,847,210

WEB TENSION CONTROLLING MEANS FOR USE IN ASSOCIATION WITH PRINTING MACHINES Filed Dec. 6 1954 s She'ets-Sheet 2 INVf/VTOR ATTORNEYS Aug. 12, 1958 A. M. HALLEY 2,847,210 WEB TENSION CONTROLLING MEANS FOR us: IN- ASSOCIATION WITH PRINTING MACHINES Filed Dec. 6. 1954 3 Sheets-Sheet 3 ATTORNEYS United States Patent Ofiic'e 2,847,210 Patented Aug. 12, 1958 WEB TENSION CONTROLLING MEANS FOR USE IN ASSOCIATION WITH PRFNTIN G MACHINES Angus Murray Halley, Moseley, Birmingham, England Application December 6, 1954, Serial No. 473,404

Claims priority, application Great Britain December 14, 1953 6 Claims. (Cl. 271--2.3)

This invention relates to an improved means for maintaining a substantially constant tension on a web being fed to or from a printing machine, and has for its object to provide a means for this purpose which can be utilised with thin and relatively fragile webs, such as foil, without breakage of the web due to the smooth manner in which the rate of feed of the web is changed to maintain the tension substantially constant.

The invention consists of means for maintaining a substantially constant tension on a web being fed to a printing and like machine wherein a tensioning roll bears upon a portion of the web between two positively driven rolls around which the web passes, characterised by the said tensioning roll being movable in accordance with the length of web between two positively driven rolls to determine the setting of an arm which in turn determines the direction of rotation of a control disc for varying the speed of rotation of one of said positively driven rolls.

An embodiment of the present invention will now be described with reference to the accompanying drawings which illustrate the application of the invention for use in connection with a printing machine.

In the drawings Fig. 1 is a side elevation of that part of the machine which incorporates the mechanism of the present invention.

Fig. 2 is an end elevation of the mechanism seen in Fig. I viewed from the left hand side, but omitting the roll from which the web is withdrawn.

Fig. 3 is a sectional plan on line 3-3 of Fig. 1.

Fig. 4- is a part sectional elevation of a variable pulley mechanism for ensuring the'constant tension on the web, and

Fig. 5 is an end elevation of Fig. 4 viewed from the right hand side.

In the illustrated embodiment of the invention the web a is wound oif a roll b and is ultimately fed to a printing machine, but it will be appreciated that the web might be fed to another form of machine other than a printing machine. The web a passes over a positively driven roll c hereinafter referred to as the variable speed roll against the periphery of which it is gripped by a parallel co-operating idle roller d. After passing over the variable speed roll 0 the Web a passes under a tensioning roll e and then around idle rollers ff to the positively rotated feed rolls (not shown) of the printing machine.

The disposition of the rolls c and fi is such that the tensioning roll e is positioned within a downwardly directed loop a of the web a, and this tensioning roll is carried by a pair of slidable bearing guide blocks g adapted to slide up and down between the parallel guide tubes h whereby the weight or a proportion of the weight of the roll e bears against the looped part a of the web a and applies a predetermined tension thereto.

The bearing guide blocks g are connected to the links of a pair of continuous chains 1' each chain meshing with a pair of sprocket wheels kk which are fixed on spindles 2 which are rotatably mounted in the bracket ll secured on the tubes h whereby the guide bearing blocks g are caused to move vertically in unison. The chains 1' are each provided with a variable counter weight 1' It will be appreciated that if the relative speed of rotation of the variable speed roll 0 is different from the speed of rotation of the feed rolls associated with the printing machine then the length of the looped web between the two rolls 0 and will vary and cause the tensioning roll e to move up or down due to the shortening or lengthening of the loop a in which it is accommodated.

Associated with one of the slidable bearing guide blocks g and laterally projecting therefrom is a pin g which is adapted to co-operate with one or other of a pair of contacts mm which contacts are adjustably mounted on the oppositely directed limbs of a rocking arm n which pivots about the fulcrum n secured to one of the tubes 11. The extremity of the upper limb of the rocking arm n is located in co-operative relationship to a rotatable cross member which operates a switch mechanism 0 and through a circuit determines the setting of the armature of a solenoid p of an electromagnet, the solenoid being pivotally connected through a link q to a rocker arm 1', hereinafter referred to.

The variable speed roll 0 is driven from a V pulley c through a V belt connection s which is associated with a variable pulley t, which is driven through a constant speed pulley u from a motor.

The variable pulley t is formed in two parts t and t respectively, so that by moving the part t axially relative to the part t the efiective diameter of the pulley can be varied, that is to say by moving the part i axially relative to the part t the V belt s is permitted to move further toward the centre of the pulley and change the ratio of the drive. The parts tt of the variable pulley t are connected by means of pins t which are axially slidable within sockets in the drum associated with the part t of the pulley. Surrounding the pins t are coiled springs t which serve to urge the two parts t and t apart. The distance apart of the two parts is determined by a rotatable screw threaded disc v which engages an externally threaded portion W of the shaft w about which the axially slidable part of the pulley is mounted. An anti-friction bearing 1 is located between the axially movable part of the pulley and the disc v.

When the rotatable disc v is in its midway position a plain portion of the periphery thereof v (see Fig. 5) ex tends over an arc of approximately 10 on either side of the top dead centre and the adjacent portions of the periphery on either side of this arc are provided with peripheral ratchet teeth v the remainder of the periphery of the disc being plain.

The ratchet teeth v are oppositely directed and have an upward disposition. Above the disc is disposed a pair of oppositely directed pawls x which are pivotally mounted independently about the same centre x on a two arm lever y which is connected by the link z to a crank driven by the constant speed motor which drives the variable speed roll 0.

In facial abutment with the control disc v and rockable about the axis of this Wheel is the arm r, hereinbefore referred to, the upper edge of which is arcuate and projects slightly beyond the periphery of the disc v while the lower end of this arm is linked as previously stated to the armature of the solenoid p.

The aforesaid arrangement is such that when the solenoid p is energized the arm r is rocked in accordance with variations in the tension appliedto the looped part a of the web a whereby one or other of the pawls x is maintained in engagement with the appropriate ratchet teeth 1/ of the control disc v.

It.will be understood, that since the two armed lever y on which the pawls x are mounted is being rocked to and fro, the control disc v is intermittently rotated in one or other directionthrough the pawl and ratchet connection referred to, while the variable speed roll c is being rotated. Since the control disc v which is mounted on the screw threaded portion of the shaft w serves to control the setting of the axially movable portion t of the variable pulley, the speed of rotation of the variable speed roll 2 is always gradually increasing or decreasing according to the position of the armature of the solenoid p which operates the arm r which in turn controls which one of the pair of pawls x is permitted to engage the ratchet teeth v on the periphery of the control disc v.

In operation let it be assumed that the control disc v is in the. mid position as seen in Fig. of the drawings, and that. the variable speed roll c is rotated at a speed slightly in excess of the speed of the printing machine, and the setting ofthe armature of the solenoid p is such that the speed of rotation of the variable speed roll 0 is gradually increasing. In such condition it will be appreciated that the loop a in which the tension roll e is located will gradually increase in length and the tension roll willmove downwardly until the pin g associated with the guide block g reaches the contact m and rocks the arm n to operate the switch mechanism 0 controlling the circuit through the solenoid p. When this condition obtains the arm r is-moved about its axis and reverses the setting of the pawls x and thereby changes the direction of rotation of the control disc v and thus through the variable pulley t changes the ratio of drive to the variable speed roll c. This results in intermittent rotation in the opposite direction of the control disc v, and the speed of rotation of the variable speed roll c will gradually be reduced until the tension roll e moves upwardly to operate the upper contact in and again reverse the direction of movement of the armature of the solenoid 2.

If desired the web a passing around the idle roller 1 may be passed over a measuring roll 1. This measuring roll is disposed. in a loop in a similar manner to the tensioning roll 0 and is carried by pivotal arms f which are connected to a spring balance i to provide an indication of the tension of the web a.

I claim:

1. In mechanism for maintaining a substantially constant tension on a web through variation in the extent of a loop thereof while the web is moving, and wherein there is a drive, for the web; said drive comprising a driven device composed of a constant speed input pulley and a coaxial variable speed output pulley consisting of one member secured to said input pulley and a coacting second member non-rotatably and axially slidably mounted on said one member, a control element rotatably screw-threaded on said driven device coaxially of said pulleys and also axially slidable thereon in different directions through and according to the variation in said loop, and a movable part mounted on said driven device providing a motion transmitting connection between said control element and said second output pulley member operable through the axial movement of said element to relatively adjust said output pulley members to cause an increase or decrease in the speed of said drive.

2. In the mechanism defined in claim 1, said control element comprising a toothed member, and constantly operating drive pawl means responsive to variations in said loop from a predetermined size for operably engaging said toothed member and rotating it in either direction for varying said drive speed until said loop is restored to said size.

3. In mechanism for maintaining a substantially constant tension one web through variation in the extent of a loop thereof While theweb is moving and wherein there is a drive for the web; said drive comprising a rotatable driven part, a shaft extending from said part provided with screw-threads, a rotatable control element having screw-threads in engagement with the first screwthreads and axially slidable on said shaft in opposite directions through and according to the variations in said loop, a variable speed pulley consisting of one member fixed to said shaft and a second member non-rotatably mounted on and slidable axially of said shaft, a motion transmitting connection between said control element and said second pulley member, a lever, linkage under constant speed control adapted to rock said lever, first and second pawl means carried by said lever, said control element having first and second teeth for the reverse driving thereof through coaction respectively with said first and second pawl means, an arm rockably mounted on said shaft to reverse said first and second pawl means, and solenoid-actuated linkage under control of said loop to operate said arm.

4. In mechanism for maintaining a substantially constant tension in a moving web wherein the web passes over a drive roller and is formed with a loop, means for driving said roller comprising a driven pulley having an axially extending shaft, a variable speed pulley comprising one side member fixed to said driven pulley and a second side member axially slidable of said shaft and non-rotatable with respect to said shaft, a rotatable control element screw threaded on said shaft and operably connected to said second pulley member to move the latter in either direction along said shaft, forward and reverse sets of drive teeth on said control element, a pair of constantly driven drive pawls each adapted to engage one of said sets of drive teeth, a shiftable selector element for effecting the engagement of one or the other of saidpawls with the associated set of drive teeth, a solenoid actuator for said selector element, and a circuit for said solenoid containing a switch responsive to a change in said loop from a predetermined size.

5. In apparatus for maintaining constant tension on a moving web, a feed roll engaging said web, means providing a loop in the web on the delivery side of said roll and a roller mounted in said loop, means for driving said roll comprising a variable speed pulley having one side constantly driven and the other side non-rotatably and axially slidably connected to said one side, a shiftable control member for said other pulley side, means providing a continuously operating intermittent drive mechanism adapted to be connected to said control member to shift said control member to relatively adjust said pulley sides to vary the drive speed thereof, and means responsive to change in the position of said roller upon a change of said loop from a predetermined size for reversibly connecting said intermittent drive mechanism to said control member or disabling said connection when the loop is restored to said size.

6. In the apparatus defined in claim 5, said roller being slidably mounted in vertical guides and suspended in said loop, and said last named means comprising a solenoid actuated selector for said mechanism having a circuit containing reversible switch means operated by displacement of said roller when the loop changes in size.

References Cited in the file of this patent UNITED STATES PATENTS 1,916,467 Eger July 4, 1933 2,568,431 Congdon Sept. 18, 1951 FOREIGN PATENTS 480,841 Great Britain Feb. 28, 1938 OTHER REFERENCES Reeves Automatic Production Control, by Reeves Pulley Company, Columbus, Indiana, booklet T-361-5M- 1-36, page 10. 

